Internal release agents, active hydrogen containing mixtures which contain such agents and the use thereof in a process for the production of molded products

ABSTRACT

The present invention is directed to a novel internal release agent, a mixture of isocyanate reactive materials containing the release agent and a RIM process using the release agent. The novel release agent is an ester prepared by reacting a specific tetrol with a mixture of a saturated and an unsaturated acid.

BACKGROUND OF THE INVENTION

Internal mold release agents used in the production of moldedpolyurethane and polyurea products are known. Many of the known internalrelease agents are based at least in part on fatty acid esters. Typicalof such release agents are those described in U.S. Pat. Nos. 3,726,952,3,925,527, 4,058,492, 4,098,731, 4,201,847, 4,254,228, 4,868,224 and4,954,537, and British Patent 1,365,215.

U.S. Pat. Nos. 4,519,965 and 4,581,386 describe the use of zinccarboxylates as internal mold release agents for the production ofmolded polyurethane and/or polyurea elastomers.

While these types of internal release agents have met with some success,they are not totally satisfactory for many applications. Twoshortcomings of all internal release agents to date, including thosedescribed above, are i) the inability to release from a bare metal mold,such as steel or aluminum, and ii) the incompatibility of such agentswith other additives typically used in the reaction injection molding("RIM") process.

DESCRIPTION OF THE INVENTION

The present invention is directed to a novel internal mold releaseagent, an active hydrogen containing mixture which contains such agent,and the use thereof in a reaction injection molding ("RIM") process. Thenovel release agents herein comprise an ester having an acid number of15 or less, and preferably 10 or less, prepared by reacting (a) one moleof a tetrahydroxy compound prepared by reacting one mole of a C₂ to C₈alkylene diamine, preferably a C₂ or C₃ alkylene diamine, with from 4 to12 moles, and preferably 4 to 6 moles, of an alkylene oxide, with (b)four moles of an acid mixture consisting of at least one saturatedmonocarboxylic acid and at least one unsaturated monocarboxylic acid,with the molar ratio of saturated to unsaturated acid being from 1:1 to3:1, and preferably 1:1.

It has been found that the product gives excellent release from avariety of different mold surfaces. Excellent release occurs when themold surface has been pre-sprayed with an external release agent. It hasalso been found that release from a bare metal mold, such as steel oraluminum, is possible without any pre-application of external moldrelease agent to the mold surface. Finally, the preferred release agentsherein are compatible with active hydrogen containing mixtures which aretypically used in the preparation of reaction injection molded ("RIM")parts.

In one preferred embodiment, the esters are mixed with a zinccarboxylate containing from 8 to 24 carbon atoms per carboxylate group.When a zinc carboxylate is used, the weight ratio of the ester to thezinc carboxylate is from about 10:1 to about 3:1, preferably from about9:1 to about 4:1.

The esters useful herein have acid numbers of 15 or less, and Preferably10 or less, and are prepared by reacting certain tetrahydroxy compoundswith specific acid mixtures. The amines used to prepare the tetrahydroxycompounds are alkylene diamines of the formula:

    H.sub.2 N--R--NH.sub.2

where R is a C₂ to C₈ straight or branched chain alkylene group. Usefuldiamines include ethylene diamine and the various straight and branchedchain isomers of diaminopropane, diaminobutane, diaminopentane,diaminohexane, diaminoheptane, and diaminooctane. Specific usefuldiamines include 1,2- and 1,3-diaminopropane; 1,3-, 2,3-, and1,4-diaminobutane; 1,2-diamino-2-methyl propane; 1,5-diaminopentane;1,4-diamino-1-methylbutane; 1,4-diamino-2-methylbutane;1,3-diamino-1-ethylpropane; 1,3-diamino-1,1-dimethylpropane;1,3-diamino-1,2-dimethylpropane; 1,3-diamino-2,2-dimethylpropane;1,5-diamino-2-methylpentane; 1,6-diaminohexane and the like. It ispresently preferred to use ethylene diamine.

The tetrahydroxy compounds useful herein are known and are prepared byreacting the above noted diamines with alkylene oxides such as ethyleneand propylene oxide. Propylene oxide is the presently preferred alkyleneoxide. In general, the tetrahydroxy compounds are prepared by reactingone mole of the diamine with from 4 to 12 moles, preferably from 4 to 6moles, of the alkylene oxide. It is generally preferred to use theminimum amount of alkylene oxide needed to react with all the hydrogensattached to the nitrogen atoms since it is particularly desirable tomaximize the weight of the acid portion of the ester in the releaseagent herein. Accordingly, it is most preferred to use only four or fivemoles of the alkylene oxide.

The tetrahydroxy compounds are then reacted with a mixture of saturatedand unsaturated monocarboxylic acids. In general, the preferredsaturated monocarboxylic acids are those containing one or more alkylgroups of from 4 to 22 carbon atoms. Most preferred are saturatedaliphatic fatty o monocarboxylic acids such as stearic acid, isostearicacid, palmitic acid, undecanoic acid, neodecanoic acid, caproic acid,capric acid, myristic acid, pentanoic acid, heptanoic acid, caprylicacid, nonanoic acid, dodecanoic acid, tridecanoic acid, 2-methylbutanoicacid, pivalic acid, 2-ethylhexanoic acid and the like. Stearic acid isthe presently preferred saturated monocarboxylic acid.

In general, the preferred unsaturated monocarboxylic acids are thosecontaining one or more alkyl groups of from 4 to 22 carbon atoms. Mostpreferred are unsaturated aliphatic fatty monocarboxylic acids such aspalmitoleic acid, 10-undecenoic acid, 4-decenoic acid, caproleic acid,myristoleic acid, 5-tetradecenoic acid, lauroleic acid, oleic acid,erucic acid and the like. Oleic acid is the presently preferredunsaturated monocarboxylic acid.

The acids may be reacted with the tetrahydroxy compound sequentially or,preferably, as a mixture of the two acids. The reaction of themonocarboxylic acids with the tetrahydroxy compound is generally carriedout at temperatures of from 40° to 220° C., preferably from 100° to 215°C., under excess pressure, reduced pressure, or, preferably in thesubstantial absence of pressure. A catalyst may be added after the waterstops distilling over, with dibutyl tin oxide being the preferredcatalyst. While the reaction time is dependent upon o the nature andamounts of starting materials, reaction times of from 2 to 8 hours aregenerally sufficient. The reaction is considered complete when the acidnumber is less than 15 and preferably less than 10.

General techniques for the preparation of the esters of the type usefulherein are generally known and are described in U.S. Pat. Nos.4,201,847, 4,254,228, and 3,925,527, the disclosures of which are hereinincorporated by reference.

As noted, in one preferred embodiment, the reaction product of thepolyester and the monocarboxylic acid are mixed with a zinc carboxylate.Useful zinc carboxylates are known in the art and are described in U.S.Pat. Nos. 4,519,965 and 4,581,386, the disclosures of which are hereinincorporated by reference. Zinc stearate is the presently preferred zinccarboxylate.

The release agents of the present invention are eminently suitable foruse in the RIM process. As is known, in the RIM process, an isocyanate,and active hydrogen containing compounds are mixed and injected intomolds, where the reactants are allowed to react fully.

Starting polyisocyanate components for use in the RIM process includealiphatic, cycloaliphatic, araliphatic, aromatic and heterocyclicpolyisocyanates of the type described, for example, by W. Siefken inJustus Liebigs Annalen der Chemie, 562, pages 72 to 136. Specificexamples of useful ethylene diisocyanate; 1,4-tetramethylenediisocyanate; 1,6-hexamethylene diisocyanate; 1,12-dodecanediisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3- and-1,4-diisocyanate and mixtures of these isomers. Additional examplesinclude 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane(German Auslegeschrift 1,202,785 and U.S. Pat. No. 3,401,190), 2,4- and2,6-hexahydrotolylene diisocyanate and mixtures of these isomers.Hexahydro-1,3- and/or -1,4-phenylene diisocyanate; perhydro-2,4'- and/or-4,4'-diphenylmethane diisocyanate; 1,3- and 1,4-phenylene diisocyanate;1,4- and 2,6-tolylene diisocyanate and mixtures of these isomers arealso suitable in the instant invention. Diphenylmethane-2,4- and/or-4,4'-diisocyanate; naphthylene- 1,5-diisocyanate; triphenylmethane-4,4',4"-triisocyanate; polyphenyl polymethylene polyisocyanatesof the type obtained by condensing aniline with formaldehyde, followedby phosgenation and described, for example, in British Patents 874,430and 848,671 may also be used in the present invention; m- andp-isocyanato-phenyl-sulfonyl isocyanates according to U.S. Pat. No.3,454,606; perchlorinated aryl polyisocyanates of the type described,for example, in German Auslegeschrift 1,157,601 (U.S. Pat. No.3,277,138); polyisocyanates containing carbodiimide groups of the typedescribed in German Patent 1,902,007 (U.S. Pat. No. 3,152,162);diisocyanates of the type described in U.S. Pat. No. 3,492,330; andpolyisocyanates containing allophanate groups of the type described, forexample, in British Patent 993,890, in Belgian Patent 761,626 and inpublished Dutch Application 7,102,524 are still further examples ofsuitable isocyanates. Additionally, polyisos cyanates containingisocyanurate groups of the type described, for example, in U.S. Pat. No.3,001,973; in German Patents 1,022,789; 1,222,067 and 1,027,394 and inGerman Offenlegungsschriften 1,929,034 and 2,004,408; polyisocyanatescontaining urethane groups of the type described, for example, inBelgian Patent 752,261 or in U.S. Pat. No. 3,394,164; polyisocyanatescontaining acylated urea groups according to German Patent 1,230,778 andpolyisocyanates containing biuret groups of the type described, forexample, in German Patent 1,101,394 (U.S. Pat. Nos. 3,124,605 and3,201,372) and in British Patent 889,050 are also suitable.

Polyisocyanates produced by telomerization reactions of the typedescribed, for example, in U.S. Pat. No. 3,654,106; polyisocyanatescontaining ester groups of the type described for example, in BritishPatents 965,474 and 1,072,956, in U.S. Pat. No. 3,567,763 and in GermanPatent 1,231,688; reaction products of the above-mentioned isocyanateswith acetals according to German Patent 1,072,385 and polyisocyanatescontaining polymeric fatty acid residues, according to U.S. Pat. No.3,455,883 are still further examples of suitable isocyanate.

Aromatic polyisocyanates which are liquid at the processing temperatureare preferably used. The particularly preferred starting polyisocyanatesinclude derivatives of 4,4'-diisocyanato-diphenylmethane which areliquid at room temperature, for example, liquid polyisocyanatescontaining urethane groups of the type obtainable in accordance withGerman Patent 1,618,380 (U.S. Pat. No. 3,644,457). These may be producedfor example, by reacting 1 mol of 4,4'-diisocyanatodiphenylmethane withfrom 0.05 to 0.3 moles of low molecular weight diols or triols,preferably polypropylene glycols having a molecular weight below 700.Also useful are diisocyanates based on diphenylmethane diisocyanatecontaining carbodiimide and/or uretone imine groups of the typeobtainable, for example, in accordance with German Patent 1,092,007(U.S. Pat. No. 3,152,162). Mixtures of these preferred polyisocyanatescan also be used. In general, aliphatic and cycloaliphatic isocyanatesare less suitable for the purposes of the instant invention.

Also preferred are the polyphenyl-polymethylene polyisocyanates obtainedby the phosgenation of an aniline/formaldehyde condensate.

Also necessary for preparing molded products via the RIM process areisocyanate reactive components. These components may be typicallydivided into two groups, high molecular weight compounds having amolecular weight of 400 to about 10,000 and low molecular weightcompounds, i.e. chain extenders, having a molecular weight of 62 to 399.Examples of suitable high molecular weight compounds include thepolyesters, polyethers, polythioethers, polyacetals and polycarbonatescontaining at least 2, preferably 2 to 8 and most preferably 2 to 4isocyanate-reactive groups of the type known for the production ofpolyurethanes.

The high molecular weight polyethers suitable for use in accordance withthe invention are known and may be obtained, for example, bypolymerizing epoxides such as ethylene oxide, propylene oxide, butyleneoxide, tetrahydrofuran, styrene oxide or epichlorohydrin in the presenceof BF₃ or by chemically adding these epoxides, preferably ethylene oxideand propylene oxide, in admixture or successively to componentscontaining reactive hydrogen atoms such as water, alcohols or amines.Examples of alcohols and amines include the low molecular weight chainextenders set forth hereinafter, 4,4'-dihydroxy diphenyl propane,sucrose, aniline, ammonia, ethanolamine and ethylene diamine. It ispreferred to use polyethers which contain substantial amounts of primaryhydroxyl groups in terminal positions (up to 90% by weight, based on allof the terminal hydroxyl groups present in the polyether). Polyethersmodified by vinyl polymers, of the type formed, for example, bypolymerizing styrene or acrylonitrile in the presence of polyether (U.S.Pat. Nos.3,383,351; 3,304,273; 3,523,093; and 3,110,695; and GermanPatent 1,152,536), are also suitable, as are polybutadienes containingOH groups.

In addition, polyether polyols which contain high molecular weightpolyadducts or polycondensates in finely dispersed form or in solutionmay be used. Such modified polyether polyols are obtained whenpolyaddition reactions (e.g., reactions between polyisocyanates andamino functional compounds) or polycondensation reactions (e.g., betweenformaldehyde and phenols and/or amines) are directly carried out in situin the polyether polyols.

Suitable examples of high molecular weight polyesters include thereaction products of polyhydric, preferably dihydric alcohols(optionally in the presence of trihydric alcohols), with polyvalent,preferably divalent, carboxylic acids. Instead of using the freecarboxylic acids, it is also possible to use the correspondingpolycarboxylic acid anhydrides or corresponding polycarboxylic acidesters of lower alcohols or mixtures thereof for producing thepolyesters. The polycarboxylic acids may be aliphatic, cycloaliphatic,aromatic, and/or heterocyclic and may be unsaturated or substituted, forexample, by halogen atoms. The polycarboxylic acids and polyols used toprepare the polyesters are known and described for example in U.S. Pat.Nos. 4,098,731 and 3,726,952 herein incorporated by reference in theirentirety. Suitable polythioethers, polyacetals, polycarbonates and otherpolyhydroxyl compounds are also disclosed in the above-identified U.S.Patents. Finally, representatives of the many and varied compounds whichmay be used in accordance with the invention may be found for example inHigh Polymers, Volume XVI, "Polyurethanes, Chemistry and Technology," bySaunders-Frisch, Interscience Publishers, New York, London, Vol. I,1962, pages 32-42 and 44-54, and Volume II 1964, pages 5-6 and 198-199;and in Kunststoff-Handbuch, Vol. VII, Vieweg-Hochtlen, Carl HanserVerlag, Munich, 1966, pages 45-71.

Suitable aminopolyethers which may be used in accordance with thepresent invention as high molecular weight compounds (the molecularweight is always the average molecular weight which may be calculatedfrom the functionality and the content of isocyanate-reactive groups)are those wherein at least about 30 and preferably about 60 to 100equivalent % of the isocyanate-reactive groups are primary and/orsecondary (preferably primary) aromatically or aliphatically (preferablyaromatically) bound amino groups and the remainder are primary and/orsecondary aliphatically bound hydroxyl groups.

In these compounds, the terminal residues carrying the amino groups mayalso be attached to the polyether chain by urethane or ester groups.These "aminopolyethers" are prepared by methods known per se. Forexample, polyhydroxypolyethers such as polypropylene glycol ethers maybe aminated by reaction with ammonia in the presence of Raney nickel andhydrogen (Belgian Patent 634,741). U.S. Pat. No. 3,654,370 describes theproduction of polyoxyalkylene polyamines by reaction of thecorresponding polyol with ammonia and hydrogen in the presence of anickel, copper, chromium catalyst. German Patent 1,193,671 describes theproduction of polyethers containing terminal amino groups byhydrogenation of cyanoethylated polyoxypropylene ethers. Other methodsfor the production of polyoxyalkylene (polyether) amines are describedin U.S. Pat. Nos. 3,155,728 and 3,236,895 and French Patent 1,551,605.The production of polyethers containing terminal secondary amino groupsis described, for example, in French Patent 1,466,708.

Polyhydroxypolyethers of relatively high molecular weight may beconverted into the corresponding anthranilic acid esters by reactionwith isatoic acid anhydride, as described, for example, in GermanOffenlegungschriften 2,019,432 and 2,619,840 and in U.S. Pat. Nos.3,808,250, 3,975,428 and 4,016,143. Polyethers containing terminalaromatic amino groups are formed in this way.

According to German Offenlegungschrift 2,546,536 and U.S. Pat. No.3,865,791, relatively high molecular weight compounds containingterminal amino groups are obtained by reaction of NCO prepolymers basedon polyhydroxypolyethers with enamines, aldimines or ketiminescontaining hydroxyl groups and subsequent hydrolysis.

It is preferred to use amino polyethers obtained by hydrolysis ofcompounds containing terminal isocyanate groups, for example inaccordance with German Offenlegungschrift 2,948,419 or U.S. Pat. No.4,515,923, herein incorporated by reference in its entirety. In thisprocess, polyethers most preferably containing 2 to 4 hydroxyl groupsare reacted with polyisocyanates to form NCO prepolymers and, in asecond step, the isocyanate groups are converted by hydrolysis intoamino groups.

Also useful are amino compounds prepared by reacting the correspondingpolyol with a halogenated nitrobenzene compound such as o- orp-nitrochlorobenzene, followed by the reduction of the nitro group(s) tothe amine as described in U.S. application Ser. No. 183,556, filed onApr. 19, 1988, and in published European Application 0,268,849,published Jun. 1, 1988.

The "aminopolyethers" used in accordance with the invention are oftenmixtures of the compounds mentioned by way of example and (on astatistical average) most preferably contain 2 to 4 terminalisocyanate-reactive groups. In the process according to the invention,the "aminopolyethers" may be used in admixture withpolyhydroxypolyethers free from amino groups.

In accordance with the present invention, the high molecular weightcompounds can be used in admixture with up to about 95% by weight basedon the total quantity of active hydrogen containing compounds, of lowmolecular weight chain extenders. Examples of suitable hydroxylgroup-containing chain extenders include ethylene glycol, 1,2- and1,3-propane diol, 1,3- and 1,4- and 2,3-butane diol, 1,6-hexane diol,1,10-decane diol, diethylene glycol, triethylene glycol, tetra-ethyleneglycol, dipropylene glycol, tripropylene glycol, glycerol andtrimethylol propane.

Preferred chain extenders are amine terminated chain extenders. Suitableamine chain extenders include aromatic polyamines, preferably diamines,having molecular weights of less than 400, especially the stericallyhindered aromatic polyamines, preferably diamines, having molecularweights of less than 400, especially the sterically hindered aromaticdiamines which contain at least one linear or branched alkyl substituentin the ortho-position to the first amino group and at least one,preferably two linear or branched alkyl substituents containing from 1to 4, preferably 1 to 3, carbon atoms in the ortho-position to a secondamino group. These aromatic diamines include1-methyl-3,5-diethy12,4-diamino benzene,1-methyl-3,5-diethyl-2,6-diamino benzene, 1,3,5-trimethyl-2,4-diaminobenzene, 1,3,5-triethyl-2,4-diamino benzene,3,5,3',5'-tetraethyl-4,4'-diamno diphenylmethane,3,5,3',5'-tetraisopropyl-4,4'-diamino diphenylmethane,3,5-diethyl-3',5'-diisopropyl-4,4'-diamino diphenylmethane,3,5-diethyl-5,5'-diisopropyl-4,4'-diamino diphenylmethane,1-methyl-2,6-diamino-3-isopropylbenzene and mixtures of the abovediamines. Most preferred are mixtures of 1-methyl-3,5-diethyl-2,4-diamino benzene and 1-methyl-3,5-diethyl-2,6-diamino benzene in aweight ratio between about 50:50 to 85:15, preferably about 65:35 to80:20.

In addition, aromatic polyamines may be used in admixture with thesterically hindered chain extenders and include, for example, 2,4- and2,6-diamino toluene, 2,4'and/or 4,4'-diaminodiphenylmethane, 1,2- and1,4-phenylene diamine, naphthalene-1,5-diamine andtriphenylmethane-4,4',4"-triamine. The difunctional and polyfunctionalaromatic amine compounds may also exclusively or partly containsecondary amino groups such as 4,4'-di-(methylamino)-diphenylmethane or1-methyl-2-methylamino-4-amino-benzene. Liquid mixtures of polyphenylpolymethylene-polyamines, of the type obtained by condensing anilinewith formaldehyde, are also suitable. Generally, the nonstericallyhindered aromatic diamines and polyamines are too reactive to providesufficient processing time in a RIM system. Accordingly, these diaminesand polyamines should generally be used in combination with one or moreof the previously mentioned sterically hindered diamines or hydroxylgroup-containing chain extenders.

Other additives which may be used in the RIM process according to thepresent invention include catalysts, especially tin(II) salts ofcarboxylic acids, dialkyl tin salts of carboxylic acids, dialkyl tinmercaptides, dialkyl tin dithioesters and tertiary amines. Preferredamong these catalysts are dibutyl tin dilaurate and1,4-diazabi-cyclo-(2,2,2)-octane (triethylene diamine), especiallymixtures of these catalysts. The catalysts are generally used in amountsof about 0.01 to 10%, preferably about 0.05 to 2%, based on the weightof the isocyanate reactive component. In some instances, such as wherethe compatibilizer contains tertiary amine groups, no additionalcatalyst may be necessary.

It is also possible to use surface-active additives such as emulsifiersand foam stabilizers. Examples include N-stearyl-N',N'-bis-hydroxyethylurea, oleyl polyoxyethylene amide, stearyl diethanol amide, isostearyldiethanolamide, polyoxyethylene glycol monoleate, apentaerythritol/adipic acid/oleic acid ester, a hydroxy ethyl imidazolederivative of oleic acid, N-stearyl propylene diamine and the sodiumsalts of castor oil sulfonates or of fatty acids. Alkali metal orammonium salts of sulfonic acid such as dodecyl benzene sulfonic acid ordinaphthyl methane sulfonic acid and also fatty acids may also be usedas surface-active additives.

Suitable foam stabilizers include water-soluble polyether siloxanes. Thestructure of these compounds is generally such that a copolymer ofethylene oxide and propylene oxide is attached to a polydimethylsiloxane radical. Such foam stabilizers are described in U.S. Pat. No.2,764,565. In addition to the catalysts and surface-active agents, otheradditives which may be used in the molding compositions of the presentinvention include known blowing agents, cell regulators, flame retardingagents, plasticizers, dyes, fillers and reinforcing agents such as glassin the form of fibers or flakes or carbon fibers. In addition, otherknown internal mold release agents may be blended with the reactionproducts herein. In most cases, and except for the instance where zinccarboxylates are mixed with the reaction products, it i$ preferred touse the reaction products alone without the addition of any otherinternal mold release agent.

The molded products of the present invention are prepared by reactingthe components in a closed mold. The compositions according to thepresent invention may be molded using conventional processing techniquesat isocyanate indexes ranging from as low as 90 to as high as 400(preferably from 95 to 115) and are especially suited for processing bythe RIM process. In general, two separate streams are intimately mixedand subsequently injected into a suitable mold, although it is possibleto use more than two streams. The first stream contains thepolyisocyanate component, while the second stream contains theisocyanate reactive components and any other additive which is to beincluded. According to the present invention, the internal release agentis added to the isocyanate reactive components. The release agentsherein are generally used in amounts ranging from about 4% to about 12%by weight, based on the weight of all the isocyanate reactivecomponents. This amount of release agent should be used even if mixturesof reaction product of polyester and monocarboxylic acid and zinccarboxylate are used.

The invention is further illustrated but is not intended to be limitedby the following examples in which all parts and percentages are byweight unless otherwise specified.

EXAMPLES

IMR 1: (1 mole tetrol:1 mole stearic:3 moles oleic) A twelve liter flaskwas charged with 2181 parts of a tetrol (the tetrol was a commerciallyavailable material sold as Multranol 4050 from Mobay Corporation;Multranol 4050 is a reaction product of ethylene diamine and propyleneoxide having an OH number of about 630). Nitrogen was bubbled throughthe flask and the temperature was raised to 130° C. 1707 parts ofstearic acid and 5084 parts of oleic acid were slowly added withstirring. The temperature was raised to 215° C. after the addition ofthe acids was complete. Water was collected in a receiving flask. Whenthe water stopped distilling over, vacuum was slowly applied to thesystem, and more water was distilled over (a total of 420 parts of waterwas collected). Full vacuum was then applied for about two hours andsamples withdrawn for acid number analysis by titration. The reactionsequence was monitored by InfraRed analysis. Disappearance of thehydroxyl absorbance signalled the end of the reaction. The final producthad an acid number of about 6.

IMR 2: (1 mole tetrol:2 moles stearic:2 moles oleic) A twelve literflask was charged with 2181 parts of the same tetrol used for IMR 1.Nitrogen was bubbled through the flask and the temperature was raised to130° C. 3484 parts of stearic acid and 3459 parts of oleic acid wereslowly added with stirring. The temperature was raised to 215° C. afterthe addition of the acids was complete. Water was collected in areceiving flask. When the water stopped distilling over, vacuum wasslowly applied to the system, and more water was distilled over (a totalof 415 parts of water was collected). Full vacuum was then applied forabout two hours and samples withdrawn for acid number analysis bytitration. The reaction sequence was monitered by InfraRed analysis.Dissappearance of the hydroxyl absorbance signalled the end of thereaction. The final product had an acid number of about 4.

IMR 3: (1 mole tetrol:3 mole stearic:1 moles oleic) A twelve liter flaskwas charged with 2137 parts of the same tetrol used in IMR 1. Nitrogenwas bubbled through the flask and the temperature was raised to 130° C.5121 parts of stearic acid and 1695 parts of oleic acid were slowlyadded with stirring. The temperature was raised to 215° C. after theaddition of the acids was complete. Water was collected in a receivingflask. When the water stopped distilling over, vacuum was slowly appliedto the system, and more water was distilled over (a total of 425 partsof water was collected). Full vacuum was then applied for about twohours and samples withdrawn for acid number analysis by titration. Thereaction sequence was monitered by InfraRed analysis. Disappearance ofthe hydroxyl absorbance signalled the end of the reaction. The finalproduct had an acid number of about 8.

IMR 4: (1 mole tetrol:4 moles oleic) A twelve liter flask was chargedwith 2000 parts of the same tetrol used in IMR 1. Nitrogen was bubbledthrough the flask and the temperature was raised to 130° C. 6344 partsof oleic acid were slowly added with stirring. The temperature wasraised to 215° C. after the addition of the acids was complete. Waterwas collected in a receiving flask. When the water stopped distillingover, vacuum was slowly applied to the system, and more water wasdistilled over (a total of 400 parts of water was collected). Fullvacuum was then applied for about two hours and samples withdrawn foracid number analysis by titration. The reaction sequence was moniteredby InfraRed analysis. Disappearance of the hydroxyl absorbance signalledthe end of the reaction. The final product had an acid number of about7.

RIM EXAMPLES

In the RIM examples which follow, the following materials:

POLYOL A: a 28 OH number polyether prepared by reacting glycerin with amixture of propylene oxide and ethylene oxide (weight ratio of propyleneoxide to ethylene oxide was about 5:1) and having a primary OH groupcontent of about 88%.

DETDA: an 80/20 mixture of 1-methyl-3,5-diethyl-2,4-and 2,6-phenyldiamine.

POLYOL B: a reaction product of ethylene diamine and propylene oxidehaving an OH number of about 630.

ZNS: zinc stearate.

DMT: dimethyl tin dilaurate.

DBT: dibutyl tin dilaurate.

TED: a 33% solution of triethylene damine in dipropylene glycol.

L5304: a silicone surfactant available from Union Carbide.

ISO: Mondur PF, available from Mobay corporation; a liquid isocyanate,having an NCO content of about 23%, prepared by reacting tripropyleneglycol with 4,4'-diphenylmethane diisocyanate.

RIM plaques were prepared using a laboratory piston metering unit andclamping unit. The metering unit was a two component instrument having amaximum metering capacity of 0.6 liters. A 300 mm×200 mm×4 mmrectangular mold was used to mold the samples. The mold was firststripped with a mold cleaner (N-methyl pyrrolidinone), then soaped withChemtrend 2006 (available from Chemtrend), and buffed twice. An aluminumtransducer plate (5.5 mm radius) was connected to a force transducermounted in the lid of the mold. The plate was soaked in DMF for an hour,polished with fine steel wool, rinsed with water, and then rinsed withacetone. A RIM shot was then made, and at the appropriate demold time,the lid of the mold was slowly opened. The maximum force required topull the transducer plate from the molded plaque is the release force.The lower the number, the easier the release. The following modlingconditions were used:

    ______________________________________                                        Mold Temperature:      65° C.                                          Component B Temperature:                                                                             45° C.                                          Component A Temperature:                                                                             45° C.                                          Demold time:           45 seconds                                             ______________________________________                                    

RIM Examples 1 through 7

The formulations used were as set forth in TABLE 1 (Examples 1, 2 and 3are comparative examples):

                  TABLE 1                                                         ______________________________________                                               EXAMPLE                                                                       1    2       3      4     5    6     7                                 ______________________________________                                        B-Side:                                                                       POLYOL A 78.3   72.3    72.3 71.55 71.55                                                                              73.8  73.8                            DETDA    16.5   16.5    16.5 16.5  16.5 16.5  16.5                            POLYOL B 3.0    3.0     3.0  3.0   3.0  3.0   3.0                             ZNS      2.0    --      --   --    --   1.0   0.5                             DBT      0.1    --      --   --    --   --    --                              DMT      --     0.1     0.1  0.1   0.1  0.1   0.1                             TED      0.1    0.1     0.1  0.1   0.1  0.1   0.1                             IMR 2    --     --      --   --    8.0  4.0   4.0                             IMR 3    --     --      --   8.0   --   --    --                              IMR 1    --     8.0     --   --    --   --    --                              IMR 4    --     --      8.0  --    --   --    --                              L5304    --      0.75    0.75                                                                              1.5   1.5  1.5   1.5                             A-Side:                                                                       ISO      50.5   49.9    49.9 49.5  49.5 50.1  50.1                            ______________________________________                                    

In each instance, 20 consecutive shots were attempted, with the moldrelease force measured in Newtons for each shot. The average releaseforces were as follows:

Example 1: 450 after 20 shots

Example 2: 507 after 7 shots

Example 3: 662 after 4 shots

Example 4: 198 after 20 shots

Example 5: 284 after 20 shots

Example 6: 108 after 20 shots

Example 7: 286 after 20 shots

As can be seen IMR 1 (Example 2) and IMR 4 (Example 3) did not providegood release. In fact, the system from Example 2 stuck to the mold after7 shots while the system from Example 3 stuck to the mold after 4 shots.IMR 2 and 3 gave excellent release. IMR 3 was not very compatible withthe components of the B-side, and thus from a commercial viewpoint wouldnot be a preferred release agent.

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

What is claimed is:
 1. A novel release agent comprising an ester havingan acid number of 15 or less, prepared by reacting (a) one mole of atetrahydroxy compound prepared by reacting one mole of a C₂ to C₈alkylene diamine with from 4 to 12 moles of an alkylene oxide, with (b)four moles of an acid mixture consisting of at least one saturatedmonocarboxylic acid and at least one unsaturated monocarboxylic acid,with the molar ratio of saturated to unsaturated acid being from 1:1 to3.1.
 2. A novel release agent is recited in claim 1, wherein(1) saidalkylene oxide is selected from the group consisting of ethylene oxideand propylene oxide; (2) said saturated monocarboxylic acid is selectedfrom the group consisting of saturated monocarboxylic acids containingone ore more alkyl groups of from 4 to 22 carbon atoms; and (3) saidunsaturated monocarboxylic acid is selected from the group consisting ofunsaturated monocarboxylic acids containing one or more alkyl groups offrom 4 to 22 atoms.
 3. An active hydrogen group containing mixturecomprising:(a) one or more compounds having molecular weights of from400 to 10,000 and containing at least two isocyanate reactive groups,(b) one or more compounds having molecular weights of 62 to 399containing at least two isocyanate reactive groups, and (c) from about 4to about 12% by weight based upon the amount of components a) and b) ofan ester having an acid number of 15 or less, prepared by reacting (1)one mole of a tetrahydroxy compound prepared by reacting one mole of aC₂ to C₈ alkylene diamine with from 4 to 12 moles of an alkylene oxide,with (2) four moles of an acid mixture consisting of at least onesaturated monocarboxylic acid and at least one unsaturatedmonocarboxylic acid, with the molar ratio of saturated to unsaturatedacid being from 1:1 to 3:1.
 4. An active hydrogen group containingmixture as recited in claim 3, wherein:(1) said alkylene oxide isselected from the group consisting of ethylene oxide and propyleneoxide; (2) said saturated monocarboxylic acid is selected from the groupconsisting of saturated monocarboxylic acids containing one or morealkyl groups of from 4 to 22 carbon atoms; and (3) said unsaturatedmonocarboxylic acid is selected from the group consisting of unsaturatedmonocarboxylic acids containing one or more alkyl groups of from 4 to 22carbon atoms.
 5. In a process for the preparation of a molded productcomprising mixing an isocyanate and an active hydrogen containingmaterial to form a reaction mixture, injecting said reaction mixtureinto a mold via the RIM process, allowing said reaction mixture to fullyreact to form said molded product, and removing said molded product fromsaid mold, the improvement wherein said reaction mixture contains fromabout 4 to about 12% by weight based upon the amount of active hydrogencontaining material of an ester having an acid number of 15 or less,prepared by reacting (1) one mole of a tetrahydroxy compound prepared byreacting one mole of a C₂ to C₈ alkylene diamine with from 4 to 12 molesof an alkylene oxide, with (2) four moles of an acid mixture consistingof at least one saturated monocarboxylic acid and at least oneunsaturated monocarboxylic acid, with the molar ratio of saturated tounsaturated acid being from 1:1 to 3:1.
 6. In a process for thepreparation of a molded product as recited in claim 5, wherein(1) saidalkylene oxide is selected from the group consisting of ethylene oxideand propylene oxide; (2) said saturated monocarboxylic acid is selectedfrom the group consisting of saturated monocarboxylic acids containingone or more alkyl groups of from 4 to 22 carbon atoms; and (3) saidunsaturated monocarboxylic acid is selected from the group consisting ofunsaturated monocarboxylic acids containing one or more alkyl groups offrom 4 to 22 carbon atoms.